In general, a continuous casting process is a process in which molten steel is continuously injected into a mold having a predetermined shape, and then the molten steel that is semisolidified within the mold is continuously drawn to a lower side of the mold to manufacture semifinished products having various shapes such as a slab, a bloom, and a billet. Since cooling water circulates in the mold, the injected molten steel is semisolidified to form a predetermined shape. That is, the molten steel that is in a molten state is semisolidified by a primary cooling effect in the mold, and the non-solidified molten steel drawn from the mold is solidified by the cooling water sprayed from a secondary cooling bed installed at a lower portion of the mold to extend, thereby forming a slab that is completely solid state.
The primary cooling in the mold is the most important factor in determining of surface quality of the slab. That is, the primary cooling may be under the control of the flow of the molten steel within the mold. In general, a mold flux is applied on the molten steel meniscus to lubricate between the molten steel and an inner wall of the mold and maintain a temperature of the molten steel. However, when a fast flow or bias flow occurs on the molten steel meniscus within the mold, the mold flux may be inserted and mixed to cause defects of the slab.
Thus, to prevent the defects of the slab due to the flow of the meniscus from occurring, it is necessary to measure the flow of the molten steel meniscus within mold in real-time during the casting process. However, since the molten steel is maintained in a high-temperature state within the mold, it is difficult to measure a flow pattern (or a flow pattern or a flow form) of the meniscus in real-time. Also, since the mold flux is applied to the molten steel meniscus, it is difficult to allow a worker to confirm and observe the molten steel meniscus by using naked eyes or a camera.
A technology for measuring a height of a meniscus through an eddy current level meter (ECLM) using an electromagnetic induction coil to control the height of the meniscus by using the measured height as disclosed in Korean Patent Registration No. 10-1244323 is being used as a method for detecting a meniscus flow of molten steel within a mold. However, in the above-described method, since only a height of any one point is measured, it is impossible to measure the molten steel flow on the entire meniscus.
Also, since a slab varies in width according to a size of the desired slab, it is difficult to measure a meniscus form in real-time due to the varying slab.